The most common application for which probes are requested is that of cortical recording. Although many different cortical areas are being explored (motor, visual, auditory), the preparations share similarities and problems which make collaborations with the Center and between external investigators increasingly important. Along with providing standard probes for acute cortical recording, the Center is working with collaborators to come up with probes, connectors, chamber designs and preparations for long-term implants. The challenges encountered in most of these preparations include placement of multiple devices into a single cranial chamber; maintaining positional stability of the probes; and inhibition of tissue encapsulation around the cable or 3-D platform due to healing of the cranium and dura. Several of the above collaborators continue to work on cranial chambers designed to hold several integrated cable/probes (either 2-D or 3-D) which protrude from the chamber edge into the cortical area. Some of the fixtures include a removable cap for access to the implants for inspection, cleaning and/or probe replacement. In the area of probe stability, collaborators are working with adhesives such as cyanoacrylate and fibrin glue to anchor the probes to the brain's surface. As discussed in the Highlights section, the University of Michigan Materials Science and Engineering is also developing biological "glues" as well as materials which will inhibit tissue adhesion to apply to probe substrates. Surgical methods such as tenting of the dura over the probe insertions are being explored as well.